Enhancement for power-down sequence

ABSTRACT

When a cellular telephone is powered down, it sends a power-down message to a network it was registered with. If the cellular telephone does not receive an acknowledgement of the power-down message from the network, a flag is set in the cellular telephone. The power-down sequence is concluded by the cellular telephone, and the cellular telephone is shut off or put into a reduced power consumption state. When the telephone is turned back on the flag is evaluated to see if it was set during the course of powering down. The status of the flag when the phone is powered up is then used by the cellular telephone to determine whether it should make a network access request to a network the telephone was registered to, during the power-up operation in order to cause that cellular network to update its database regarding the whereabouts of the powered-up cellular telephone.

BACKGROUND

FIG. 1 depicts a prior art wireless communication system. The system 100is comprised of a communications tower 102 at the top of which is anantenna 104. Radio frequency signals 106 emanate from, and are picked upby the antenna 104 in the course of providing two-way wirelesscommunications to compatible communications devices, such as aconventional cellular telephone 108 in a motor vehicle 110 or which canbe carried about by a person, not shown.

In FIG. 1, the cellular telephone 108 in the vehicle 110 provides bothtwo-way voice communications to users of a motor vehicle 110 andtelematics data services to the motor vehicle 110. A telematics dataservice is a wireless data connection between sensors located on avehicle 110 and a service provider that monitors the state of suchsensors via a connection provided by a cellular telephone or othercompatible wireless communications network. The General Motors ON-STAR™system is an example of a telematics data service.

The cellular telephone 108 maintains communication with a cellularnetwork, not shown, by the radio frequency signals that are exchangedbetween the cellular radio 108 and the antenna 104 so long as thecellular radio 108 is within a geographic coverage area 110 or cellwithin which radio communications with a cellular radio 108 can bemaintained.

When the cellular radio 108 is powered down, it sends a power-down orde-registration message 112 to a cellular network controller, not shown,via the tower 102 service the cell 110 within which the cellulartelephone 108 is operating. When the cellular system receives thepower-down or de-registration signal 112, the cellular systemacknowledges the power-down message 112 by the transmission of anacknowledgment message or “ACK” message, which when received by thecellular telephone 108 notifies the telephone 108 that the power-downsequence was received by the network. On the other hand, it a responseto a power down, de-registration message 112 is not received by thecellular telephone 108, it will subsequently power-up in anindeterminate state vis-a-vis the network. The network might not knowwhether the cellular telephone 108 is “present” on the system or withinthe cell 110 or otherwise reachable. Among other things, text messagestransmitted to the telephone 108 while it was powered down (off) mightbe sent to the telephone 108 by the network without the network beingable to determine whether the messages were actually received. A methodand apparatus for avoiding the ambiguity and operating state when acellular radio powers-down but does not receive an acknowledge signalfrom the network would be an improvement over the prior art.

BRIEF SUMMARY

In accordance with embodiments of the invention, when a cellulartelephone is powered down, it sends a power-down message to a network itwas previously registered with. If the network does not send, or if thecellular telephone does not receive, an acknowledgement of thepower-down message from the network, a status bit referred to as a flagis set (or reset) in a non-volatile memory device in the cellulartelephone. The power-down sequence is concluded by the cellulartelephone and, the cellular telephone is shut off or put into a reducedpower consumption state. When the telephone is turned back on, i.e.,returned to its previous state, the flag is evaluated or “tested” to seeif it was set (or reset) during the course of powering down. The statusor value of the flag when the phone is powered up is then used by thecellular telephone to determine whether it should make a network accessrequest to a network the telephone was registered to, during thepower-up operation in order to cause that cellular network to update itsdatabase regarding the whereabouts of the powered-up cellular telephone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a prior art wireless communication system;

FIG. 2 is a block diagram of an apparatus for restoring wirelesscommunications to a wireless communications device;

FIG. 3 is a flowchart of a part of a method of restoring wirelesscommunications to a wireless communications device after the device hasbeen powered down;

FIG. 4 depicts an alternate method of restoring wireless communicationto a wireless communications device; and

FIG. 5 is a power-up sequence.

DETAILED DESCRIPTION

FIG. 2 is a block diagram of an apparatus 200 for restoring wirelesscommunications to a wireless communications device, such as a cellulartelephone, after the wireless communications device is powered-down. Theapparatus 200 is comprised of a conventional, prior art wirelesscommunications system transmitter 202 and a conventional prior artwireless communications system receiver 204. The transmitter 202 and thereceiver 204 are both coupled to a conventional prior art antenna 206through a conventional duplexer (not shown) to which is coupled aconventional transmission line 208.

A user interface 210 includes, but is not limited to, a conventionaltelephone handset, a speaker phone and a display device, through which aperson can place and receive telephone calls and/or send and receivetext and data messages via radio frequency signals sent to and receivedfrom a communication end point, such as a telematics service provider,another cell phone, or a data network. A communication end point is notshown in the figures for brevity.

The apparatus is also comprised of a processor 212, which is connectedto and thereby controls at least the transmitter 202, the receiver 204,and the user interface 210 via a conventional prior art address, dataand control bus 214. As used herein, the term “bus” refers toelectrically parallel conductors or circuits that connect components ofa computer system to each other and which allow the transfer of electricimpulse energy from one connected component to another. The bus 214 thusconnects the transmitter 202, receiver 204 and user interface 210 andthe processor 212 inter-operatively to each other.

As shown in the figure, the bus 214 is also coupled between theprocessor 212 and a non-volatile memory device 216. In an alternateembodiment however, wherein the processor is part of a single-chipmicrocontroller or microprocessor, the processor 212 can be connected tothe non-volatile memory device 216 via a separate bus 218 commonly foundin single chip microcontrollers and microprocessors and which connects acentral processing unit to a memory devices that are co-located with theCPU on the same silicone substrate.

A telematics system controller 220 embodied as a separate computer orprocessor, monitors the state of various vehicle sensors to which thetelematics system controller 220 is connected by way of severaldifferent connections 224. Such sensors can include accelerometers ortilt sensors, collision or impact sensors, air bag deployment sensorsand the like. If the telematics system controller 220 receives a signalfrom a monitored sensor, it is configured to direct the processor 212 ofthe apparatus 200, to cause the transmitter 202 to broadcast anappropriate notification message to a telematics service provider, notshown. Control signals provided to the processor 212 from the telematicssystem controller 220 are preferably carried over a separate bus 226connected between the telematics system controller 220 and the processor212.

In at least one alternate embodiment, the processor 212 is configured toperform the functionality of a separate telematics system controller220. In such an embodiment, the processor 212 would have additionalinput/output ports or memory-mapped input/output ports that allow theprocessor 212 to monitor the state of various inputs and sensors.

In a preferred embodiment, the processor 212 is configured to receive asignal on an input port 228 the logical condition of which directs orcauses the processors 212 to power-up or power-down the communicationapparatus 200. Powering down the apparatus 200 occurs when a vehicle isshut-off in order to save power and reduce battery drain.

When a power-down signal is received by the processor 212, the processor212 is configured to execute program instructions stored within it orthe non-volatile memory 216, which when executed cause the processor 212to execute an enhanced power-down sequence. When the apparatus 200 ispowered up, the enhanced power-down sequence enables the apparatus 200to be able to quickly determine whether a network that the apparatus 200had been registered with, acknowledged the apparatus' state change frompowered up to powered down.

Program instructions in one or more non-volatile memory devices, such asdevice 216, and which are coupled to the processor 200, when executed,cause the processor to effectuate the transmission of a conventionalpower-down or de-registration message, from the transmitter 202 to awireless communication network with which communication between theapparatus 200 and such network had previously been established. Afterthe power-down message is transmitted, additional program instructionscause the processor to enter a wait state or wait condition for a fixedand predetermined period of time during which the processor 212continuously polls or scans the receiver 204 for receipt of anacknowledgement signal, also known as an “ACK” signal, sent from awireless communications network, indicating to the apparatus 200 thatthe network received the power-down message and that the network willde-register the apparatus 200 from the network thus preventing thenetwork from trying to route calls and messages to the apparatus afterit has fully powered down.

The enhanced power-down sequence is comprised in part of programinstructions in the non-volatile memory 216, which when executed, causethe processor 212 to set (or reset) one or more binary digits (bits) ina register 230 co-located on the substrate with the processor 212 or,set (or reset) one or more bits in one or more memory locations 232 in anon-volatile memory device 216. The setting or resetting of one or morebinary digits is considered herein to be setting a “flag” the state ofwhich is subsequently used in a power-up sequence to determine whetheran acknowledgement of a power-down message was received by the apparatus200. The flag is considered herein to be a network response message,status flag.

One or more binary digits are set or reset as the case may be if thereceiver 204 does not detect the receipt of an acknowledgment by thewireless communication network to the de-registration message, which isalso referred to herein after as a power-down registration message. Ifthe power-down registration message is not received, it is likelybecause a network that the apparatus was registered to, did not receiveor failed to process a power-down or de-registration message. Thenetwork will thus continue to treat the apparatus as if it is stillpowered up and operating.

Program instructions in the non-volatile memory device 216 control theprocessor 212 during its power-up sequence, causing the processor 212 tocheck the status of the network response message status flag todetermine whether the previously transmitted power-down registrationmessage was acknowledged by a network.

FIG. 3 is a flowchart of a part of a method 300 of restoring wirelesscommunications to a wireless communications device after the device hasbeen powered down. The method 300 can be performed by the apparatus inFIG. 2 and equivalents thereof.

At an initial step 302, the communications device or apparatus 200 isfunctioning normally and continues to do until a power-down message isinput to the device, as happens when a user depresses a shut-down orpower-off button on a conventional cell phone or a vehicle user turnsoff the vehicle's ignition. At step 304 a power-down command is receivedby the apparatus. After the power-down command is received at step 304the method 300 proceeds to step 306 whereat a power-down orde-registration message is transmitted by the apparatus 200 to a networkto which the apparatus 200 had been previously registered with. Once thepower-down registration message is transmitted, the wireless deviceshould receive an acknowledgement, albeit within a finite period of timethat is typically established by network service providers but which canalso be operationally programmed into the communications apparatusitself. It can also be programmed by the user or operator of the device.

Step 308 depicts the establishment of a network response message,time-out timer limit. The time-out timer limit can be specified by aservice provider, a phone manufacturer or even an input by a user.Nevertheless, once a power-down registration message is transmitted atstep 306, the wireless communications device or apparatus 200 shouldreceive an acknowledgement (ACK) within a finite time thereafter. Thattime limit is depicted in FIG. 3 as being set at step 308.

Step 310 shows that if the acknowledgement response is received, themethod 300 proceeds to step 312 where the wireless communications devicecompletes the execution of its power-down sequence. The apparatus 200then goes into a sleep, stand-by or complete shut-down mode at step 314,where it stays until the device is powered up.

If after sending the power-down registration message at step 306, anacknowledgement is not received immediately, the method 300 proceeds tostep 316 where the time-out timer count value is decremented in a loopcomprised of steps 310, 316 and 318. If the time-out timer value isexceeded, which means that no acknowledgement to the power-downregistration has been received within the time period previouslyestablished, at step 318 the method proceeds to step 320 where theprocessor sets a network response message flag described above, whichwhen set indicates to the apparatus upon power up that noacknowledgement message was received in response to thepreviously-executed power-down sequence. After the flag is set, themethod 300 proceeds to finish its power down sequence at step 312.

FIG. 4 depicts an alternate method 400 of restoring wirelesscommunication to a wireless communications device or apparatus 200 afterthe apparatus has been sent a power-down command. From its normaloperating mode 402, the apparatus 200 receives a power-down command atstep 404, which causes the device or apparatus 200 to initiate itspower-down sequence at 406. Near the end of the power-down sequence 406,but as a part of that sequence, a power-down, de-registration message istransmitted from a transmitter 202 at step 408. The method of FIG. 3 andmethod of FIG. 4 thus differ by whether the power-down registrationmessage is sent before or after the initiation of the power-downsequence.

As with the method shown in FIG. 3, a response time-out timer limit isset at step 410. Thereafter, the method immediately checks for thereception of an acknowledgement at step 412. If a response is received,the method shown in FIG. 4 finishes the power-down sequence at step 414.If no acknowledgement is received, at 412 the time-out timer isdecremented at step 416, checked for exhaustion at step 418 and if thetime has exhausted or expired, and no acknowledgement has been receiveda no acknowledgement flag is set at step 420 and the power-down sequenceconcluded as before at step 414.

Setting a “flag” to indicate that a power-down ACK signal was notreceived enables a wireless communications device to quickly determineupon power up whether the a previously-transmitted power-downregistration message was received. If the flag is set (or reset) apreviously registered-to network might consider the device to have beenregistered with the network for the entire time that the apparatus 200was powered down.

Referring now to FIG. 5, a power-up sequence 500 is shown. When apower-up message or command is detected at step 502, as happens when auser presses the power-on button of his cellular telephone or thevehicle ignition is turned on, the device attempts to register with alocal network in step 504 using conventional prior art techniques forregistering a wireless communications device with a wirelesscommunications network. At step 506, and after registration has beenaccomplished, the method 500 checks to determine whether theacknowledgement flag described above has been “set” indicating whetheran acknowledgement to a previously-transmitted power-down registrationmessage was received and acknowledged by the wireless network. If theflag is set, the wireless communications device thus knows that it needsto request a network access in order to notify the network of itsexistence. At step 508, the method initiates a method access request,such as requesting a voice channel, by which the registered-to network(step 504) becomes aware of the wireless communications device andnotifies a home network of its existence. If the flag is not set asdetermined at step 506, the wireless communications device enters itsnormal operating state at step 510 as happens after the network accessrequest is made at step 508.

Those of ordinary skill in the art to which the appurtenant claims aredirected will recognize that a power-down state and a power-downsequence are device and system dependent. In some embodiments, apower-down state will be an operating state where power consumption isreduced by not zero. In other embodiments, a power-down state existswhen no power is being consumed.

Those of ordinary skill in the art will recognize that the setting of astatus bit or bits can be effectuated by setting one or more bits toeither a logic 1 or a logic 0. A flag can also be embodied as more thanone bit. Stated another way, the polarity of one or more binary digitsin a memory device or a register that indicate either the reception ofan ACK signal or the failure to receive an ACK signal, is a designchoice. The bit or bits comprising a flag can be either a logic 1 or alogic 0.

The foregoing description is for purposes of illustration only. The truescope of the invention is set forth in the following claims.

1. A method of restoring wireless communications to a wirelesscommunications device, after the device is powered down, the methodcomprising: transmitting a power-down registration message to thenetwork; waiting for a network response message; if a network responsemessage is received, powering down the device according to a power downsequence; if a network response message is not received, setting a flagwithin the device and powering down the device according to said powerdown sequence.
 2. The method of claim 2, further comprising the stepsof: powering up the device after completion of the power down sequence;registering with a local wireless communications network; determiningwhether the flag was set: if the flag was set, initiating a networkaccess request of the local wireless communications network.
 3. Themethod of claim 2, wherein the step of determining whether the flag wasset occurs prior to the step of registering with a local wirelesscommunications network.
 4. The method of claim 2, wherein the step ofinitiating a network access request comprises: transmitting a datapacket.
 5. The method of claim 4, wherein the step of transmitting adata packet comprises a short message service data packet.
 6. The methodof claim 2, wherein the step of initiating a network access requestcomprises: initiating a voice call.
 7. The method of claim 1, whereinthe step of setting a flag comprises: writing a binary value to a memorydevice.
 8. The method of claim 1, further comprising the step of:initiating the power down sequence prior to the step of transmitting apower-down registration message to the network.
 9. The method of claim8, wherein the step of: initiating a power down sequence is responsiveto a message received from a telematics controller.
 10. An apparatus forrestoring wireless communications to a wireless communications device,after the device is powered down, the apparatus comprising: atransmitter, configured to transmit a power-down registration message; areceiver, configured to receive a network response message; a processorcoupled to the receiver and configured to wait for a received responseto the power-down registration message and: if a response message isreceived, the processor being configured to power down the deviceaccording a power down sequence; if a network response message is notreceived, the processor setting a flag and thereafter powering down thedevice according to said power down sequence.
 11. The apparatus of claim10, wherein the processor is additionally configured to: power up thedevice after completion of the power down sequence; register with alocal wireless communications network; determine whether the flag wasset: if the flag was set, initiate a network access request of the localwireless communications network.
 12. The apparatus of claim 10, furthercomprising a memory device, operatively coupled to the processor andconfigured to store a signal representative of the flag.
 13. Theapparatus of claim 10, further comprising a telematics controllercoupled to the processor and configured to reduce power consumption by avehicular telematics system.
 14. An apparatus for restoring wirelesscommunications to a wireless communications device, after the device ispowered down, the apparatus comprising: a wireless communicationsdevice; a processor coupled to the wireless communications device andcontrolling the wireless communications device; a memory device coupledto the processor and containing program instructions, which, whenexecuted, cause the wireless communications device to: transmit apower-down registration message to the network; wait for a networkresponse message; if a network response message is received, power downthe device according to a power down sequence; if a network responsemessage is not received, set a flag within the device and power down thedevice according to said power down sequence.
 15. The apparatus of claim14, wherein the memory device contains program instructions, which whenexecuted cause the device to: power up the device after completion ofthe power down sequence; register with a local wireless communicationsnetwork; determine whether the flag was set: if the flag was set,initiate a network access request of the local wireless communicationsnetwork.
 16. The apparatus of claim 14, further comprising a telematicscontroller coupled to the processor and configured to reduce powerconsumption by a vehicular telematics system.